Green’s Dictionary of Slang

everything, a large amount or quantity, e.g. cost the earth, pay the earth, want the earth.

1890		Music Hall & Theatre Rev. 4Jan. 6/1: Pat Rafferty wants the earth, as the Yanks say.
1898		Binstead & Wells A Pink ’Un and a Pelican 231: Let’s try and find a cabman that doesn’t want the earth.
1966		T. Keyes All Night Stand 55: They mix it up themselves [...] and charge you the earth for it.
1975		Bulletin (Sydney) 26 Apr. 45: The poor bastard needs an earn to handle those kite blues. The law is asking the earth and he fronts next week.